Ok new message still regarding cams

[Timbo1969]

Ok I got the advise on my other posting. I'm getting ready to do a complete rebuild on my engine. I'm planning on using 12 to 1 compression, providing I can get it to work on 92 octane, 1.8 rocker arms, high energy valve springs and retainers. A level 4 port and polish with a 3 angle valve job. I'll be using a vigilante 2700 stall coverter, and a 12 bolt posi. What would be the best cam, to get the most hp and torque out of this set up?

[camaro_zach]

WOW if you are going that all out get a damn 224/224. lol. good luck with your project. ;)

[Timbo1969]

<blockquote>quote:</font><hr>Originally posted by camaro_zach:
WOW if you are going that all out get a damn 224/224. lol. good luck with your project. ;) <hr></blockquote> Hey I want 13's or better all motor..lol

[AMinor65]

Just wondering? How are you gonna get 12 to 1 compression to work on 92 octane? I am by no means an expert on compression and minimum octane ratings, but here is a chart I picked up concerning ratios and minimum octane levels:

Desired ratios and minimal octane levels
9:1=90, 10:1=94, 11:1=98, 12:1=102, 13:1=106, 14:1=110

I have a friend who has an LT1 that was shooting for a 11:1 ratio not taking into account the octane levels. His car will flat out not run on pump gas.

[98Camaro3.8]

<blockquote>quote:</font><hr>Originally posted by AMinor65:
Desired ratios and minimal octane levels
9:1=90, 10:1=94, 11:1=98, 12:1=102, 13:1=106, 14:1=110<hr></blockquote>

According to this chart, shouldn't we be running 92 octane with our 9.4:1 compression? ;)

Matt

[ March 02, 2003: Message edited by: 98Camaro3.8 ]</p>

[Boehlke]

I'm also curious to see how you can run 12:1 compression on 92. I just had my engine built w/ forged pistons running 10:1, and they said thats the max they could do and still have it run on 92. I know timing plays a role, but it seems you'd have to back of the timing so much it wouldn't be worth it...correct me if I'm wrong

[AMinor65]

<blockquote>quote:</font><hr>Originally posted by 98Camaro3.8:


According to this chart, shouldn't we be running 92 octane with our 9.4:1 compression?

Matt

[ March 02, 2003: Message edited by: 98Camaro3.8 ]<hr></blockquote>

I thought about that too when I first saw the chart. To be honest with you, I don't know. Maybe the chart is supposed to be like a "rule of thumb". I've seen it posted a few places.

[Rick M.]

Toyota Celica GT-S has 11.5:1 compression and they can run 6lbs. of boost on 91 octane and stock internals...

[Timbo1969]

<blockquote>quote:</font><hr>Originally posted by AMinor65:
Just wondering? How are you gonna get 12 to 1 compression to work on 92 octane? I am by no means an expert on compression and minimum octane ratings, but here is a chart I picked up concerning ratios and minimum octane levels:

Desired ratios and minimal octane levels
9:1=90, 10:1=94, 11:1=98, 12:1=102, 13:1=106, 14:1=110

I have a friend who has an LT1 that was shooting for a 11:1 ratio not taking into account the octane levels. His car will flat out not run on pump gas.<hr></blockquote> I'm still working on that with the shop that is doing the rebuild, they suggested 12 to 1, I was thinking 10 or 10.5 myself. Since my car is my main means of transport. I'm going to get more in depth on it. The orignal intimdator concept car ran 13 to 1's on 92 octane, so I have no idea.

[Boehlke]

<blockquote>quote:</font><hr>Originally posted by Rick M.:
Toyota Celica GT-S has 11.5:1 compression and they can run 6lbs. of boost on 91 octane and stock internals...<hr></blockquote>

You also have to take into account we have an iron block with iron heads, while the celica is all aluminum.

[HAZ-Matt]

good call

[jmorgan]

if you had aluminum heads and block you might could get away with 12:1 but your block and heads are iron the retain to much head and with 92 octain my *** you would need probly 110


your shop is stupid. find a new one if they dont know your heads and block arnt aluminum and that all they could take with 93 octain is 10.5:1 they are crazy and stupid find another shop

[WickEdSix9838]

you can run a crap load of compression on 92 octane, did ya'll see the engine masters challenge in Popular Hot Rodding magazine?? there was a guy that ran 16:1 static compression on 92 octane pump gas...its in how the cam is ground, you can have a cam ground that will lower the dynamic compression by bleeding off the extra cylinder pressure to run pump gas, as to specs to get ground, you're gonna have to call someone w/more knowledge, but it is possible...

[ March 03, 2003: Message edited by: WickEdSix9838 ]</p>

[RamAir95TA]

Stock LT1s have 10.5:1, while the LT4 has 10.8:1 (due to 4cc valve reliefs in the pistons) and both run beautifully on 92.

[Boehlke]

LT1's also have reverse cooled heads. Again, the cooler heads prevent detonation which will allow a higher compression ratio.

As far as having the cam bleed off compression, isn't that defeating the purpose of running high compression?